1. Field of the Invention
The present invention relates to an IC chip mounting structure adapted for a relatively large power consuming IC chip, which can be manufactured in mass production and with a low cost and is of good quality and high reliability, utilizing an IC chip mounting structure, typically, a flat panel display device.
2. Description of the Related Art
Among flat panel display devices, a plasma display device is suitable for reducing the thickness, enlarging the display size, and obtaining a high definition display. Therefore, a plasma display device is exemplary explained below. An AC-type plasma display device (PDP) comprises a plasma display panel including two glass substrates arranged in an opposed relation to each other, and a circuit part for driving and controlling the panel. One of the glass substrates has a plurality of parallel address electrodes, and the other glass substrate has a plurality of mutually parallel sustain electrodes extending perpendicular to the address electrodes.
Circuit boards having drive circuits are provided for applying a drive voltage to the electrodes on the glass substrates. A chassis is attached to one of the substrates, and the circuit boards are arranged on the chassis. Wiring boards (flexible printed circuit boards) are used to connect the electrodes of the glass substrates to the drive circuits. The driver IC chips are mounted on the wiring boards. In this way, a large-sized, thin plasma display device can be configured.
In the prior art, the electrodes of the driver IC chip mounted on the wiring board are connected to the wiring (conductors) of the wiring board by a wire bonding. The method using the wire bonding, however, has a low productivity as compared with the method using a flip-chip structure. For this reason, a method is desirably employed in which the electrodes of the driver IC chip are connected to the conductors of the wiring board using the flip-chip structure higher in productivity.
Also, with the plasma display device, a high drive voltage is applied to the electrodes of the glass substrates. As a result, a high voltage and a large current are supplied to the driver IC chips mounted on the wiring board so that the driver IC chips themselves generate heat. In employing a structure for connecting the electrodes of the driver IC chip to the conductors of the wiring board using the flip-chip structure, therefore, the heat radiation of the driver IC chip must be taken into consideration.
Japanese Unexamined Patent Publication No. 10-260641 discloses a configuration in which the chassis of the plasma display panel is extended longer than the normal one, and a driver IC chip is arranged on the extension. This configuration poses the problem, however, that the size of the plasma display device is further increased. Also, in the invention disclosed by this publication, one side of the driver IC chip is mounted on the flexible printed wiring board, and the other exposed side of the driver IC chip is fixed on the chassis by an adhesive tape having a superior heat conductivity. Therefore, the problem is that the driver IC chip left exposed is easily damaged if contacted by a hand or a tool.
Japanese Unexamined Patent Publication No. 2000-268735 discloses a configuration in which one of the glass substrates is extended and a driver IC chip is arranged on the extension. Also in this case, the problem is encountered that the size of the plasma display device is further increased. Also, as in the preceding case, the driver IC chip is left exposed, and therefore the problem is posed that the driver IC chip is easily damaged if contacted by a hand or a tool.
Japanese Unexamined Patent Publication No. 2000-299416 discloses a configuration in which the side of the IC chip having bump electrodes is connected face down to a flexible printed circuit board, and the other side of the IC chip is fixed to a radiation member by an adhesive. According to this publication, the IC chip is fixed to the radiation member by the adhesive, and therefore the radiation member functions as a leverage so that stress is generated in the connector between the IC chip and the flexible printed circuit board. Also, in this publication, resin is filled between the flexible printed circuit board and the radiation member to protect the IC chip. Before being fixed to the radiation member, the IC chip is handled with the flexible printed circuit board while being exposed, thereby posing the problem that it is easily damaged when the driver IC chip is contacted by a hand or a tool.
The object of the present invention is to solve the above described problems, and to provide an IC chip mounting structure adapted for a relatively large power consuming IC chip, which can be manufactured in mass production and with a low cost and is of good quality and high reliability, utilizing an IC chip mounting structure, typically, a flat panel display device.
An IC chip mounting structure, according to the present invention, comprises at least one IC chip having a first surface having electrodes formed thereon and a second surface opposite to the first surface, a wiring board having the IC chip mounted thereon and conductors connected to the electrode of the IC chip, a protective member attached to the wiring board and having an opening comprising a peripheral wall surrounding the IC chip, and a heat conductive first member arranged in the opening of the protective member in contact with the second surface of the IC chip.
A display device, according to the present invention, comprises a flat display panel comprising a pair of substrates having a plurality of electrodes, a circuit board having a circuit for supplying a drive voltage to the electrodes on one of the substrates, a chassis attached to the same substrate and having the circuit board arranged thereon, and a driver IC module mounted on the chassis for connecting the electrodes of the one of the substrates to the circuit of the circuit board. The driver IC module comprises at least one driver IC chip having a first surface having electrodes formed thereon and a second surface opposite to the first surface, a wiring board having the driver IC chip mounted thereon and conductors connected to the electrode of the driver IC chip, a protective member attached to the wiring board and including an opening comprising a peripheral wall surrounding driver IC chip, and a highly heat conductive member arranged in the opening of the protective member in contact with the second surface of the driver IC chip.
With this configuration, the driver IC chip is mounted in a flip chip structure on the wiring board. The protective member is attached to the wiring board, and the driver IC chip is surrounded by the periphery of the opening of the protective member. The height of the surrounding wall of the opening of the protective member is greater than the thickness of the driver IC chip. Even in the case where the driver IC chip is handled in the state mounted on the wiring board, therefore, the driver IC chip is not damaged by a finger or a tool. When the wiring board with the driver IC chip is mounted on the chassis, the heat conductive first member arranged on the opening of the protective member is interposed between the driver IC chip and the chassis, so that the heat generated by the driver IC chip is transmitted to the chassis through the heat conductive first member thereby to radiate the heat of the driver IC chip. On the other hand, the heat conductive first member acts as a cushion for mounting the driver IC chip on the chassis.
In addition, according to further aspects of the present invention, an IC chip mounting structure and a display device in which a driver IC chip and a wiring board having an IC chip mounted thereon can be protected.